1. Field of the Invention
The present invention relates to hydraulic presses for molding various materials.
2. Description of Prior Art
A programmable velocity and force control method of compression molding utilizing a large press, and including servo controls for the operation is shown in U.S. Pat. No. 4,076,780. This particular patent illustrates a press device that is operated mechanically, to operate a press ram, but in the final mold closing, hydraulic cylinders are used for controlling the tilting of the mold to maintain the mold parts parallel.
U.S. Pat. No. 3,531,830 shows an apparatus for forming a molded article which includes a type of camming element for regulating the position of stops which control the movement of the molding press in its final molding operation.
A molding press which includes retractable wedge members which are controlled by hydraulic cylinders is shown in U.S. Pat. No. 3,802,818. Additionally, molding machines are shown in U.S. Pat. Nos. 2,722,174 and 3,543,344; and servo hydraulic press controls are shown in U.S. Pat. No. 3,825,386.
The assignee of the present invention has done a substantial amount of work in the field of servo hydraulic controls, including controls for various apparatus which have rigid tables which need to be maintained properly relative to a reference plane. For example, U.S. Pat. No. 3,800,588 illustrates a servo control apparatus for providing a plurality of degrees of freedom control to a rigid structure. Also, variations in this type of control are shown in U.S. Pat. No. 3,918,298.
The assignee of the present application also owns patents relating to hydrostatic bearings and the controls for such bearings. This includes U.S. Pat. No. 3,921,286 and a divisional application which issued as U.S. Pat. No. 3,992,978. Further an external height control for a hydrostatic bearing is shown in U.S. Pat. No. 3,994,540.
A hydraulic cupping press for deep drawing of aluminum cups to be made into cans is shown in U.S. Pat. No. 3,908,429, and a press frame construction that is adjustable is shown in U.S. Pat. No. 4,063,453.